This record describes multibeam echosounder data collected on RV Investigator voyage IN2022_V08, titled "Biodiversity Assessment of Australia’s Indian Ocean Territories" which departed Darwin on September 30 and returned to Fremantle November 3, 2022. This was a continuation of voyage IN2021_v04. The Kongsberg EM710 MKII multibeam echosounder was used to acquire seafloor bathymetry and backscatter information and watercolumn backscatter between Darwin and Fremantle (via the Indian Ocean Territories) in areas with water depths shallower than ~1000m. The EM710 MKII provides a 0.5° by 1° transmit and receive angular resolution respectively. The echosounder's nominal frequency range is from 40 to 100 kHz. During this voyage, the frequency range was set to 70 to 100 kHz. Data are stored in *.all raw format for bathymetry and backscatter and *.wcd format for watercolumn backscatter at CSIRO. There are 138 *.all files totaling 32.6 GB of raw bathymetry/backscatter data and 135 *.wcd files totaling 233 GB of watercolumn data in this dataset. Sound velocity profiles were applied to this data during data acquisition. Bathymetry data contained in *.all format are corrected for motion and position. GPS tide was computed using the EGM2008 model and applied to the processed data. Processed data has had outliers removed. Processed line data are available in *.gsf and ascii format, and processed bathymetry grids in geotiff format. Additional information regarding this dataset, including further information on processing streams, is contained in the GSM data acquisition and processing report. Additional data products may be available on request.

This record describes XBT data collected on RV Investigator voyage IN2019_V06, titled 'Tropical observations of atmospheric convection, biogenic emissions, ocean mixing, and processes generating intra-seasonal SST variability' which departed Darwin on the 19th of October 2019 and returned to Darwin on the 17th of December 2019 ,consisting of two legs. Leg 1 - Darwin, 20:00, 19 October 2019 to Darwin, 19:00, 10 November 2019 Leg 2 - Darwin, 20:00, 11 November 2019 to Darwin, 08:00, 17 December 2019 A total of 33 XBT casts were conducted over the duration of this voyage (27 XBTs in Leg1, 6 XBTs in Leg 2). Data are stored in netCDF files at CSIRO. Additional information regarding this dataset is contained in the GSM data acquisition and processing report. Additional data products may be available on request.

This record describes sub bottom profiler data collected on RV Investigator voyage IN2019_V06, titled 'Tropical observations of atmospheric convection, biogenic emissions, ocean mixing, and processes generating intra-seasonal SST variability' which departed Darwin on the 19th of October 2019 and returned to Darwin on the 17th of December 2019 ,consisting of two legs. Leg 1 - Darwin, 20:00, 19 October 2019 to Darwin, 19:00, 10 November 2019 Leg 2 - Darwin, 20:00, 11 November 2019 to Darwin, 08:00, 17 December 2019 The Kongsberg SBP120 (sub bottom profiler) was used to acquire data containing the specular reflections at different sediment interfaces below the seafloor. The SBP120 provides a 3° by 3° angular resolution. The echosounder's frequency sweep range is from 2.5 to 7 kHz. The SBP120 was logged continuously across the voyage transits between research stations and then turned off once stationary. Data are stored in *.raw and *.segy formats at CSIRO. Leg 1 contains 787 files totalling 13.4 GB of raw data, and *.segy (780 files 13.9 GB) formats at CSIRO Leg 2 contains 894 files totalling 9.7 GB of raw data, and *.segy (886 files 9.6 GB) formats at CSIRO The segy format data had a real time processing stream applied, which applies gain, a gain correction, matched filter with replica shaping, an attribute calculation for instantaneous amplitude and time variable gain. Additional information regarding this dataset is contained in the GSM data acquisition and processing report. Additional data products may be available on request

This record describes multibeam echosounder data collected on RV Investigator voyage IN2019_v06, titled 'Tropical observations of atmospheric convection, biogenic emissions, ocean mixing, and processes generating intra-seasonal SST variability' which departed Darwin on the 19th of October 2019 and returned to Darwin on the 17th of December 2019 ,consisting of two legs. Leg 1 - Darwin, 20:00, 19 October 2019 to Darwin, 19:00, 10 November 2019 Leg 2 - Darwin, 20:00, 11 November 2019 to Darwin, 08:00, 17 December 2019 The Kongsberg EM710 multibeam echosounder was used to acquire seafloor bathymetry and backscatter information around the Northwest Shelf station (121.5 E, 14 S) for Leg 1, and between the Warruwi & Berrimah weather stations in Northern Territory for Leg 2. The EM710 provides a 0.5° by 1° transmit and receive angular resolution respectively. The echosounder's nominal frequency range is from 70 to 100 kHz. Data are stored in *.all raw format for bathymetry and backscatter and *.wcd format for watercolumn backscatter at CSIRO. Leg 1 contains 56 files totalling 9.3 GB of raw data, covering approximately 483 nautical miles and Leg 2 contains 279 files totalling 129 GB of raw data, covering approximately 1,448 nautical miles. Sound velocity profiles were applied to this data during data acquisition. Bathymetry data contained in *.all format is corrected for motion and position. Tide corrections were not applied to the processed data for Leg 1, but were applied to the processed data for Leg 2. Processed data had outliers removed. Processed line data are available in *.gsf and ascii format, and processed bathymetry and backscatter grids in geotiff format. Additional information regarding this dataset, including further information on processing streams, is contained in the GSM data acquisition and processing report. Additional data products may be available on request.

This record describes multibeam echosounder data collected on RV Investigator voyage IN2019_V06, titled 'Tropical observations of atmospheric convection, biogenic emissions, ocean mixing, and processes generating intra-seasonal SST variability' which departed Darwin on the 19th of October 2019 and returned to Darwin on the 17th of December 2019 ,consisting of two legs. Leg 1 - Darwin, 20:00, 19 October 2019 to Darwin, 19:00, 10 November 2019 Leg 2 - Darwin, 20:00, 11 November 2019 to Darwin, 08:00, 17 December 2019 The Kongsberg EM122 multibeam echosounder was used to acquire seafloor bathymetry, backscatter information and watercolumn around the Northwest Shelf station (121.5 E, 14 S) for Leg 1, however was not used in Leg 2 due to shallow water (<100m). The EM122 provides a 1 degree by 1 degree angular resolution. The echosounder's nominal frequency is 12 kHz. Data are stored in *.all raw format for bathymetry and backscatter and *.wcd format for watercolumn backscatter at CSIRO. There are 467 files totalling 36 GB of raw data in this dataset, covering approximately 1,779 nautical miles. Sound velocity profiles were applied to this data during data acquisition. Bathymetry data contained in *.all format are corrected for motion and position. Tide corrections were not applied to the processed data. Processed data had outliers removed. Processed line data are available in *.gsf and ascii format, and processed bathymetry and backscatter grids in geotiff format. Additional information regarding this dataset, including information on processing streams, is contained in the GSM data acquisition and processing report. Additional data products may be available on request.

This record describes gravity data collected on RV Investigator voyage IN2019_V06, titled 'Tropical observations of atmospheric convection, biogenic emissions, ocean mixing, and processes generating intra-seasonal SST variability' which departed Darwin on the 19th of October 2019 and returned to Darwin on the 17th of December 2019 ,consisting of two legs. Leg 1 - Darwin, 20:00, 19 October 2019 to Darwin, 19:00, 10 November 2019 Leg 2 - Darwin, 20:00, 11 November 2019 to Darwin, 08:00, 17 December 2019 The gravity meter instrument is a MicroG Lacoste Air-Sea II. Data are stored in .ENV and .DAT data files at CSIRO. There are 44 files totalling 392 MB of raw data in this dataset for Leg 1. There are 88 files totalling 680 MB of raw data in this dataset for Leg 2. Wharf tie[s] were undertaken upon returning to Darwin on gravity station 1991980532: Stokes Wharf West, using a Scintrex Autograv CG-5. Wharf tie data can be found in T011050.TXT, which is stored with the raw data. No processing has been conducted on this data. Additional information regarding this dataset is contained in the GSM data acquisition and processing report.

This record describes scientific split-beam echosounder data collected on the RV Investigator voyage IN2019_V06, titled 'Tropical observations of atmospheric convection, biogenic emissions, ocean mixing, and processes generating intra-seasonal SST variability' which departed Darwin on the 19th of October 2019 and returned to Darwin on the 17th of December 2019 ,consisting of two legs. Leg 1 - Darwin, 20:00, 19 October 2019 to Darwin, 19:00, 10 November 2019 Leg 2 - Darwin, 20:00, 11 November 2019 to Darwin, 08:00, 17 December 2019 The Simrad EK60 split beam echosounders 18, 38, 70 120, 200 and 333 kHz were used to acquire acoustic backscatter data, around the Northwest Shelf station (121.5 E, 14 S) for Leg 1 only. The port drop keel position was set to 4 m and the starboard drop keel set to flush with hull for the duration of the voyage. The EK60 was switched off on Leg 1 (00:45 23-Oct-2019) at the request of the Chief Scientist to reduce interference on the ADCP data. This remained off for the duration of Leg 2. Data are stored in *.raw, *.bot and *.idx format at CSIRO. There are 174 files totalling 8.39 GB of raw data in this dataset (note that raw_ek60 data was only collected on Leg 1) No Post-Processing has been conducted on this data. Additional information regarding this dataset is contained in the GSM data acquisition and processing report. Additional data products may be available on request.

This record describes multibeam echosounder data collected on RV Investigator voyage IN2022_V08, titled "Biodiversity Assessment of Australia’s Indian Ocean Territories", which departed Darwin on September 30 and returned to Fremantle on November 3, 2022. This was a continuation of voyage IN2021_v04. The Kongsberg EM122 multibeam echosounder was used to acquire seafloor bathymetry, backscatter information and watercolumn backscatter between Darwin and Fremantle (via the Indian Ocean Territories). The EM122 provides a 1 degree by 1 degree angular resolution. The echosounder's nominal frequency is 12 kHz. Data are stored in *.all raw format for bathymetry and backscatter and *.wcd format for watercolumn backscatter at CSIRO. There are 1195 *.all files totaling 54 GB of raw bathymetry/backscatter data and 1195 *.wcd files totaling 73.7 GB of watercolumn data in this dataset Sound velocity profiles were applied to this data during data acquisition. Bathymetry data contained in *.all format are corrected for motion and position. GPS tide was computed using the EGM2008 model and applied to the processed data. Processed data had outliers removed. Processed line data are available in *.gsf and ascii format, and processed bathymetry and backscatter grids in geotiff format. Additional information regarding this dataset, including information on processing streams, is contained in the GSM data acquisition and processing report. Additional data products may be available on request.

This record describes scientific split-beam echosounder data collected on the RV Investigator voyage IN2022_V08, titled "Biodiversity Assessment of Australia’s Indian Ocean Territories" which departed Darwin on September 30 and returned to Fremantle on November 3, 2022. This was a continuation of voyage IN2021_v04. The Simrad EK60 split beam echosounders for 18 kHz and Simrad EK80 split beam echosounders for 38, 70 120, 200 and 333 kHz were used to acquire acoustic backscatter data to a range of 250 m (shallow water) or 1500 m (deep water) between Darwin and Fremantle. All frequencies were logged continuously for the extent of the voyage, except on occasion around Cocos (Keeling) Island and Muirfield Seamount when the 70 and 120 kHz frequencies were set to passive to avoid interference with the EM710 when conducting shallow multibeam bathymetry surveys. Data are stored in *.raw, *.bot and *.idx format at CSIRO. There are 2138 files totalling 149 GB of raw data in this dataset. Additional information regarding this dataset is contained in the GSM data acquisition and processing report. Additional data products may be available on request.

This record describes sub bottom profiler data collected on RV Investigator voyage voyage IN2022_V08, titled "Biodiversity Assessment of Australia’s Indian Ocean Territories", which departed Darwin on September 30 and returned to Fremantle on November 3, 2022. This was a continuation of voyage IN2021_v04. The Kongsberg SBP120 (sub bottom profiler) was used to acquire data containing the specular reflections at different sediment interfaces below the seafloor. The SBP120 provides a 3° by 3° angular resolution. The echosounder's frequency sweep range is from 2.5 to 7 kHz. With the exception of periods when stationary (e.g. during CTD casts), the SBP120 was logged continuously for the extent of the voyage. Data are stored in *.raw (1015 files 22.2 GB) raw and *.seg (1006 files 22.1 GB) segy formats at CSIRO. The segy format data had a real time processing stream applied, which applies gain, a gain correction, and matched filter with replica shaping. Additional information regarding this dataset is contained in the GSM data acquisition and processing report. Additional data products may be available on request.